Re: camping
Agree that Rostrevor is very good for the kids - it's run by the local authority, is set in a park with playgrounds, a restaurant, forrests, and lots more.
The time we stayed there it seemed to be quite big-groupish though, whereas most other sites we have stayed in tended to be filled with individual families. The big groups made a good bit of noise at night - I'm not sure if it was just our time there or if this is normal for that place.
z